Trying a USB cable that lacks a DC line would be indeed a worth while experiment.
I believe that my Rowland Aeris DAC does not require a powered USB cable.... I need to check this with the factory. I am using a coaxial connection using an HFC Ultra... SPDIF being the superior connection for this DAC, according to the manufacturer.
Concerning PS Audio Huron driver, it is inevitable that DAC manufacturers keep leap-frogging one another with software or hardware upgrades, and retests are definitely worth while... Case in point, the audible performance of my Aeris has been enhanced by a staggring factor since I have replaced its stock power supply with the new Rowland Power Storage Unit (PSU), which is a full external chassis that feeds Aeris clean DC from a bank of ultracapacitors, resulting in Aeris operating off the AC grid 24/7.
Guido